I started a numerica1 calculation for the Pauling helix some time ago by preparing a few graphs of Cn functions, intending
to try them on the data of Mrs. Hodgkin for insulin. However, I did not get very far beyond this stage, so that if you are
going ahead with numerical calculations, it would be a pity to duplicate them here.
I think that a graphical method might be quite adequate, the evaluation being done by superimposing over the Cn graph a sheet
of tracing paper with a properly oriented square net drawn on to it, the scale of the net depending on r and its orientation
on the z co-ordinate of the atom. In this way the values of Cn are evaluated on points of a standard square net in reciprocal
space, and contributions from different atoms are thus rapidly added at each point of the net.
The Sn values can be obtained from the Cn graphs by providing a separate angular scale, say in red. I am sending you a part
of my Co graph, in case you have not already plotted one; the evaluation is, as you will see, very rapid. Do you think a
graph like this should be included in the paper, or in some subsequent papers dealing with numerical results?